feat: add typescript solution to lc problem: No.0653.Two Sum IV - Input is a BST

Author: zhaocchen

solution/0600-0699/0653.Two Sum IV - Input is a BST/README_EN.md

@@ -119,6 +119,37 @@ class Solution {
 }
 ```
 
+### **TypeScript**
+
+```ts
+/**
+ * Definition for a binary tree node.
+ * class TreeNode {
+ *     val: number
+ *     left: TreeNode | null
+ *     right: TreeNode | null
+ *     constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
+ *         this.val = (val===undefined ? 0 : val)
+ *         this.left = (left===undefined ? null : left)
+ *         this.right = (right===undefined ? null : right)
+ *     }
+ * }
+ */
+
+function findTarget(root: TreeNode | null, k: number): boolean {
+    let set: Set<number> = new Set();
+    return find(root, k, set);
+};
+
+
+function find(root: TreeNode | null, k: number, set: Set<number>): boolean {
+    if (!root) return false;
+    if (set.has(k - root.val)) return true;
+    set.add(root.val);
+    return find(root.left, k, set) || find(root.right, k, set);
+}
+```
+
 ### **C++**
 
 ```cpp